Gas pocket distributor for hydroprocessing a hydrocarbon feed stream

ABSTRACT

A distributor assembly for hydroprocessing a hydrocarbon mixture of hydrogen-containing gas and liquid hydrocarbon is presented. The distributor assembly has a circular plate with a plurality of hollow risers bound thereto for distributing hydrogen-containing gas and liquid hydrocarbon through openings in the circular plate member. Each of the hollow risers has a tubular opening in its associated side. The distributor assembly is connected to an internal wall of a reactor. A method is also presented for hydroprocessing a hydrocarbon feed stream comprising flowing a mixture of hydrogen-containing gas and liquid hydrocarbon into a reactor zone to produce evolved hydrogen-containing gas; and flowing the mixture of hydrogen-containing gas and liquid hydrocarbon through a plurality of tubular zones while admixing simultaneously therewith the evolved hydrogen-containing gas.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a gas-pocket distributor assembly fordistributing a mixture of liquid hydrocarbons and hydrogen-containinggas(es). More particularly, the present invention provides for animproved gas-pocket distributor assembly, a reactor containing theimproved gaspocket distributor assembly, and a method forhydroprocessing a hydrocarbon feed stream.

2. Description of the Prior Art

Hydroprocessing or hydrotreatment to remove undesirable components fromhydrocarbon feed streams is a well known method of catalyticallytreating such heavy hydrocarbons to increase their commercial value."Heavy" hydrocarbon liquid streams, and particularly reduced crude oils,petroleum residua, tar sand bitumen, shale oil or liquified coal orreclaimed oil, generally contain product contaminants, such as sulfur,and/or nitrogen, metals and organo-metallic compounds which tend todeactivate catalyst particles during contact by the feed stream andhydrogen under hydroprocessing conditions. Such hydroprocessingconditions are normally in the range of 212 degree(s) F to 1200degree(s) F (100 degree(s) to 650 degree(s) C.) at pressures of from 20to 300 atmospheres. Generally such hydroprocessing is in the presence ofcatalyst containing group VI or VIII metals such as platinum,molybdenum, tungsten, nickel, cobalt, etc., in combination with variousother metallic element particles of alumina, silica, magnesia and soforth having a high surface to volume ratio. More specifically, catalystutilized for hydrodemetallation, hydrodesulfurization,hydrogenitrification, hydrocracking, etc., of heavy oils and the likeare generally made up of a carrier or base material; such as alumina,silica, silica-alumina, or possibly, crystalline aluminosilicate, withone or more promoter(s) or catalytically active metal(s) (orcompound(s)) plus trace materials. Typical catalytically active metalsutilized are cobalt, molybdenum, nickel and tungsten; however, othermetals or compounds could be selected dependent on the application.

Because these reactions must be carried out by contact of ahydrogen-containing gas with the hydrocarbon feed stream at elevatedtemperatures and pressures, the major costs of such processing areessentially investment in vessels and associated furnaces, heatexchangers, distributor plate assemblies, pumps, piping and valvescapable of such service and the replacement cost of catalystcontaminated in such service, and the cost of assembling the equipment.Commercial hydroprocessing of relatively low cost feed stocks such asreduced crude oils containing pollutant compounds, requires a flow rateon the order of a few thousand up to one hundred thousand barrels perday, with concurrent flow of hydrogen at up to 10,000 standard cubicfeet per barrel of the liquid feed. Vessels capable of containing such areaction process are accordingly cost-intensive both due to the need tocontain and withstand corrosion and metal embrittlement by the hydrogenand sulfur compounds, while carrying out the desired reactions, such asdemetallation, denitrification, desulfurization, and cracking atelevated pressure and temperatures. Pumps, piping and valves forhandling fluid streams containing hydrogen at such pressures andtemperatures are also costly, because at such pressures seals mustremain hydrogen impervious over extended service periods of many months.It is also cost-intensive to insure that all of the equipment includingdistributor plate assemblies are assembled and/or manufacturedcorrectly. It is important in such prior art distributor plateassemblies that they are essentially perfectly level to immunize flowdistribution of the hydrocarbon feed streams from their sensitivity tothe levelness of the distributor plate assembly.

As particularly distinguished from prior known methods ofhydroprocessing, the method and apparatus in U.S. Pat. No. 5,076,908 toStangeland et al more specifically provides a system wherein downwardplug-flow of the catalyst bed is maintained over a wide range ofcounterflow rates of a hydrocarbon feed stream and hydrogen gasthroughout the volume of the substantially packed catalyst bed. Suchpacked bed flow maintains substantially maximum volume and density ofcatalyst within a give vessel's design volume by controlling the size,shape and density of the catalyst so that the bed is not substantiallyexpanded at the design rate of fluid flow therethrough.

The prior art does not disclose or suggest the above enumerated andpertinent features of either the total system or significant portions ofsuch a system in U.S. Pat. No. 5,076,908 to Stangeland et al, asdisclosed by the following patents:

Jacquin et al U.S. Pat. No. 4,312,741, is directed toward a catalystreplacement method in a hydroprocessing system by controlling the feedof hydrogen gas at one or more levels. Catalyst, as an ebullated bedcounterflows through the reactor but is slowed at each of several levelsby horizontally constricted areas which increase the hydrogen andhydrocarbon flow rates to sufficiently locally slow downward flow ofcatalyst. While local recycling thus occurs at each such stage, rapidthrough-flow of fresh catalyst, with resultant mixing with deactivatedor contaminated catalyst, is suppressed. The ebullating bed aids simplegravity withdrawal of catalyst from the vessel. Improvement of thedisclosed system over multiple vessels with valves between stages issuggested to avoid the risk of rapid wear and deterioration of valveseals by catalyst abrasion.

Kodera et al, U.S. Pat. No. 3,716,478, discloses low linear velocity ofa mixed feed of liquid and H₂ gas to avoid expansion (or contraction) ofcatalyst bed. By low linear velocity of fluid upflow, gas bubbles arecontrolled by flow through the packed bed, but the bed is fluidized byforming the bottom with a small cross-sectional area adjacent thewithdrawal tube. This assists discharge of catalyst without backmixingof contaminated catalyst with fresh catalyst at the top of the singlevessel. The range of bed level in the vessel is from 0.9 to 1.1 of theallowable bed volume (±10%) due to fluid flow through the bed. Aparticular limitation of the system is that flow of the fluidsundergoing catalytic reaction is restricted to a rate that will notexceed such limits, but must be adequate to ebullate the bed adjacentthe catalyst withdrawal tube. Alternatively, injection of auxiliaryfluid from a slidable pipe section is required. The patenteesparticularly specify that the diameter of the lower end of the vessel issmaller to increase turbulence and ebullation of catalyst adjacent theinlet to the catalyst withdrawal line. Fluidization of catalyst isaccordingly indicated to be essential to the process. However, thedisclosed gas flow rates are well below commercial flow rates and thereis no suggestion of temperatures or pressures used in the tests or thesize, density or shape of the catalyst.

Bischoff et al, U.S. Pat. No. 4,571,326, is directed to an apparatus forwithdrawing catalyst through the center of a catalyst bed counterflowingto a liquid hydrocarbon and gas feed stream. The system is particularlydirected to arrangements for assuring uniform distribution of hydrogengas with the liquid feed across the cross-sectional area of the bed.Such uniform distribution appears to be created because the bed isebullating under the disclosed conditions of flow. Accordingly,considerable reactor space is used to initially mix the gas andhydrocarbon liquid feeds in the lower end of the vessel before flowingto other bottom feed distributors. The feeds are further mixed at ahigher level by such distributor means in the form of "Sulzer Plates" ora "honeycomb" of hexagonal tubes beneath a truncated, conical, orpyramidal-shaped funnel screen. The arrangement may include an open ramparea parallel to the underside of the screen between the tube or plateends. Further, to maintain gas distributions along the length of thecatalyst bed, quench gas is supplied through upflowing jets instar-shaped or annular headers extending across middle portions of thevessel. The arrangement for withdrawal of spent catalyst requiresebullation of at least the lower portion of the bed. As noted above,added vessel space for uniform mixing of hydrogen and feed beforeintroducing the fluids into an ebullated bed, as well as an ebullatingbed, increases the required size of the hydroprocessing vessel,increases catalyst attrition, increases catalyst bed mixing andsubstantially increases initial, and continuing operating costs of thesystem.

Bischoff et al, U.S. Pat. No. 4,639,354, more fully describes a methodof hydroprocessing, similar to U.S. Pat. No. 4,571,326, wherein similarapparatus obtains uniform ebullation through the vertical height of acatalyst bed, including a quench gas step.

Meaux U.S. Pat. No. 3,336,217, is particularly directed to a catalystwithdrawal method from an ebullating bed reactor. In the system,catalyst accumulating at the bottom of a vessel and supported on a flatbubble-tray may be withdrawn through an inverted J-tube having aparticular ratio of the volume of the short leg of the J-tube to thelonger leg. The diameter of the J-tube is suited only to flow ofcatalyst from a body of catalyst ebullated by the upflowing hydrocarbonfeed and gas.

U.S. Pat. Nos. 4,444,653 and 4,392,943, both to Euzen, et al, discloseremoval systems for catalyst replacement in an ebullating bed. In thesepatents, the fluid charge including hydrocarbon containing gas isintroduced by various arrangements of downwardly directed jets actinglaterally against or directly onto the conical upper surface of the bedsupport screen or screens. Alternatively, the feed is introduced througha conical screen after passing through a distributor arrangement oftortuous paths or a multiplicity of separate tubes to mix the gas andliquid feed over the conical screen. Such arrangements use aconsiderable volume of the pressure vessel to assure such mixing.

U.S. Pat. Nos. 3,730,880 and 3,880,569, both to Van der Toorn, et al,disclose a series of catalytic reactors wherein catalyst movesdownwardly by gravity from vessel to vessel through check valves. Asnoted above, such valves require opening and closing to regulate therate of flow, or to start and stop catalyst transfer, with catalyst inthe valve flow path. Feed of process fluids is either co-current orcountercurrent through the catalyst bed.

Van ZijIlLanghaut et al, U.S. Pat. No. 4,259,294, is directed to asystem for continuous or periodic replacement of catalyst by entrainmentof the catalyst in oil pumped as a slurry either to withdraw catalystfrom or to supply fresh catalyst to, a reactor vessel. Reacting feed issuggested to be either co-current or countercurrent with catalyst flowthrough the reactor. Valves capable of closing with catalyst in theline, or after back-flow or slurry oil, are required to seal off thecatalyst containing vessel at operating temperatures and pressures fromthe receiving reactor vessel, or isolate the catalyst receiving lockhopper from the withdrawal section of the vessel.

Carson, U.S. Pat. No. 3,470,900, and Sikama, U.S. Pat. No. 4,167,474,respectively illustrate multiple single bed reactors and multi-bedreactors in which catalyst is replaced either continuously orperiodically. The feed and catalyst flow co-currently and/or radially.Catalyst is regenerated and returned to the reactor, or disposed of. Nocatalyst withdrawal system is disclosed apart from either theconfiguration of the internal bed support or the shape of the vesselbottom to assist gravity discharge of catalyst.

One of the basic principles and teachings of Stangeland et al in U.S.Pat. No. 5,076,908, is that by specifically selecting the size, shape,and density of the catalyst pellets, combined with appropriate controlof process liquid and gas velocities, random motion and backmixing ofthe catalyst can be minimized, and plugflow characteristics of thecatalyst downward and the liquid and gas flow upward, maximized.Stangeland et al economically utilizes space within a hydroprocessingvessel over a wide range of processing rates without substantial randommotion or ebullation of a packed bed of catalyst during high counterflowrates of the hydrocarbon feed and a hydrogen containing gas through thepacked bed, while maintaining continuous or intermittent replacement ofcatalyst for plug-like flow of the bed through the vessel. Such plugflow with high processing rates is obtained by Stangeland et al byselecting the size, shape and density of the catalyst particles toprevent ebullation and bed expansion at the design flow rate so as tomaximize the amount of catalyst in the vessel during normal operationand during catalyst transfer. Catalysts are selected utilizing datagained while studying catalyst bed expansion, such as in a large pilotplant run, with liquid hydrocarbon, hydrogen and catalyst at the designpressures and flow velocities within the available reaction volume ofthe vessel. Catalyst is removed from the bed by Stangeland et al throughlaminar flow of the catalyst particles in a liquid slurry system inwhich the liquid flow line is uniform in diameter, and substantiallylarger than the catalyst particles, throughout the flow path between thereactor vessel and a pressurizable vessel including passageways throughthe flow control valves.

However, the method and apparatus disclosed by Stangeland et al in U.S.Pat. No. 5,076,908, as well as the methods and apparatus(es) taught bythe above-identified prior art patents relating to U.S. Pat. No.5,076,908 to Stangeland, et al, all teach and/or suggest a distributorplate assembly that should be essentially level in a reactor vesselcontaining the distributor plate assembly. Flow distribution of ahydrocarbon feed stream passing through a distributor plate assembly issensitive to the levelness of the distributor plate assembly within thereactor vessel. Even for a perfectly level plate, gas flow would pulsebecause of sloshing and varying liquid level. If the distributor plateassembly is not level, distribution of the hydrocarbon feed streamthroughout an associated catalyst bed within the reactor vessel isaffected. Also, these prior art hydroprocessing methods and apparatusesare saddled at times with hydrogen-containing gas bubbles that are toolarge, which also could affect the distribution of the hydrocarbon feedstream throughout a catalyst bed within the reactor vessel. Therefore,what is needed and what has been invented is a method and an apparatusor distributor assembly that is capable of producing an excellent,steady and smooth flow of a mixture of a gas, (e.g. ahydrogen-containing gas) and a liquid (e.g. a liquid hydrocarbon) into achamber (e.g. a plenum chamber) without the indicated deficienciesassociated with the prior art methods and apparatuses.

SUMMARY OF THE INVENTION

The present invention accomplishes its desired objects by providing adistributor assembly for hydroprocessing a hydrocarbon mixture ofhydrogen-containing gas and liquid hydrocarbon flowing through ahydroconversion reaction zone containing a bed of catalyst. Thedistributor assembly includes a plate member having a structure definingat least one opening; and at least one tube member having a tubular boreand bound to the plate member such that the tubular bore communicateswith the at least one opening. The at least one tube member has a pairof open ends and at least one tubular opening in a side thereof. Thetube member has a tubular axis and the tubular opening which has anopening axis that is generally normal to the tubular axis. Theapparatus, as well as the method, of the present invention may beemployed for mixing any gas in any liquid, such as aeration ponds,adding CO₂ to reactors, etc.

The present invention further accomplishes its desired objects bybroadly providing a reactor comprising a vessel with an internalcylindrical wall; and a catalyst bed support means secured to theinternal cylindrical wall of the vessel for supporting a catalyst bed.The distributor assembly is secured to the internal cylindrical wall ofthe vessel.

The present invention also further accomplishes its desired objects byproviding a method for hydroprocessing a hydrocarbon feed stream that isflowing through a hydroconversion reaction zone having a bed ofcatalyst, which method comprises the steps of: forming at least onetubular zone in a reactor zone containing a hydrocarbon reaction zonehaving a bed of catalyst; flowing a mixture of hydrogen-containing gasand liquid hydrocarbon into the reactor zone to produce evolvedhydrogen-containing gas; and flowing the mixture of hydrogen-containinggas and liquid hydrocarbon through the at least one tubular zone whileadmixing therewith, preferably simultaneously admixing therewith, theevolved hydrogen-containing gas.

Whenever the term "evolved hydrogen-containing gas" is stated in thespecification and/or the claims, it is not to unduly limit the spiritand scope of the present invention and is intended to mean not onlyhydrogen gas that has evolved from the liquid hydrocarbon that is beingintroduced into a reactor simultaneously therewith, but also hydrogengas that did not evolve from the liquid hydrocarbon and is at least partof the hydrogen-containing gas itself that is being introduced into thereactor along with the liquid hydrocarbon. Thus, "evolvedhydrogen-containing gas" comprises the hydrogen-containing gas that isbeing introduced into a reactor along with the liquid hydrocarbon, anyhydrogen gas that has evolved from the liquid hydrocarbon itself, andhydrogen-containing gas that solutionized and/or dissolved into and/orwith the liquid hydrocarbon and which has subsequently evolved from theliquid hydrocarbon, especially after introduction into the reactor.

It is therefore an object of the present invention to provide adistributor assembly for hydroprocessing a hydrocarbon mixture ofhydrogen-containing gas and liquid hydrocarbon.

It is another object of the present invention to provide a reactorcontaining the distributor assembly for hydroprocessing a hydrocarbonmixture of hydrogen-containing gas and liquid hydrocarbon.

It is also further an object of the present invention to provide amethod for hydroprocessing a hydrocarbon feed stream that is flowing,preferably upflowing, through a hydroconversion reaction zone having abed of catalyst.

These, together with the various ancillary objects and features thatwill become apparent to those artisans skilled in the art as thefollowing description proceeds, are attained by the present invention, apreferred embodiment as shown with reference to the accompanyingdrawings, by way of example only, wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partial perspective sectional view of the reactor of thepresent invention having a distributor plate assembly with a pluralityof depending hollow risers, with each riser having an openingwherethrough evolved hydrogen-containing gas flows to be admixed with amixture of liquid hydrocarbon and hydrogen-containing gas;

FIG. 2 illustrates a mixture of hydrogen-containing gas and liquidhydrocarbon flowing into a hollow riser having an opening, with themixture not having passed the opening in the hollow riser, and furtherillustrating evolved hydrogen-containing gas passing from a suitable gashead and into a space in the hollow riser above a level of the mixtureof hydrogen-containing gas and liquid hydrocarbon contained therein;

FIG. 3 illustrates the mixture of liquid hydrocarbon andhydrogen-containing gas flowing upwardly through a hollow riser and pastthe opening in the hollow riser, with evolved hydrogen-containing gaspassing and/or flowing from a suitable gas head, through the opening inthe hollow riser and into the mixture of liquid hydrocarbon andhydrogen-containing gas for admixing with the same;

FIG. 4 is a partial cross-sectional view of the reactor in FIG. 8 ofcopending patent application Ser. No. 08/497,638 filed Jun. 30, 1995illustrating a catalytic bed with a plurality of superimposed layerswith respect to each other before commencement of a plug-flow;

FIG. 5 is a partial cross-sectional view of the reactor in FIG. 9 ofcopending patent application Ser. No. 08/497,638 filed Jun. 30, 1995, inwhich catalyst is moving downwardly in a plug-flow fashion;

FIG. 6 is an enlarged sectional-view illustrating the mixture of liquidhydrocarbon and hydrogen-containing gas flowing turbulently upwardlythrough a hollow riser and past the opening in the hollow riser, withhydrogen gas flowing from a suitable gas head, through the opening inthe hollow riser and into the turbulent flowing mixture of liquidhydrocarbon and hydrogen containing gas for admixing with the turbulentflowing mixture; and

FIG. 7 is an enlarged partial elevational sectional-view of the lowerpart of the reactor illustrating the flow of hydrogen gas and the liquidhydrocarbon.

DETAILED DESCRIPTION OF THE INVENTION INCLUDING PREFERRED AND/OR BESTMODE EMBODIMENTS OF THE INVENTION

Referring in detail now to the drawings wherein similar parts of theinvention are identified by like reference numerals, there is seen areactor vessel, generally illustrated as 10. Reactor vessel 10 includesan internal generally cylindrical wall 11 and a bottom domed closure 12with an internal surface 13. The bottom domed closure 12 is secured tothe internal generally cylindrical wall 11. The reactor vessel 10 isdesigned to react a hydrogen-containing gas 36 mixed with a liquidhydrocarbon stream 38 at a pressure of up to about 300 atmospheres(about 4500 lbs. per square inch) and up to about 650° C. (about 1200°F.). For such reaction, hydrogen-containing gas 36 and liquidhydrocarbon stream 38 are preferably premixed and introduced as a singlestream (i.e. a single two-phase flow) through the bottom domed closure12 by a conduit 14 secured coaxially thereto such as to have aconcentric disposition with respect to the reactor vessel 10.

The reactor vessel 10 contains a catalyst bed support means, generallyillustrated as 16, for supporting a catalyst bed 18 and containingappropriate openings (not shown) well known to the artisans in the art.The catalyst bed support means 16 contained in the reactor vessel 10 maybe of any suitable geometric shape, such as concentric rings, conical,pyramidal, truncated polygonal or conical, frusto-conical, etc. Thecatalyst bed support means 16 further may be of any type that preferablyinsures even and equal distribution of hydrogen-containing gas 36 andliquid hydrocarbon stream 38 across a full cross-sectional area of thecatalyst bed 18. Thus, the particular geometric shape or type of thecatalyst bed support means 16 is not to unduly limit the spirit andscope of the present invention.

To assure maximum catalytic benefit during the hydroprocessing of thehydrogen-containing gas 36 and the liquid hydrocarbon stream 38, it ispreferred that the reactor vessel 10 contain as much catalyst aspossible within the design volume of the reactor vessel 10. Accordingly,it is preferred that the catalyst bed support means 16 for the catalystbed 18 be placed as low as possible in the reactor vessel 10 whileassuring full and adequate dispersion of the hydrogen-containing gas 36within the liquid hydrocarbon stream 38.

The upper level of the catalyst bed 18 is to be controlled such thatebullation, expansion, or fluidization of the catalyst bed 18 isminimized and that undesirable excursions from the design flow rate forhydrogen-containing gas 36 and liquid hydrocarbon stream 38 flowingupwardly through the catalyst bed 18 are avoided for the selectedcatalyst. For this accomplishment and as discussed in detail in U.S.Pat. No. 5,472,928, issued Dec. 5, 1995 and which is fully incorporatedherein by reference thereto as if repeated verbatim immediatelyhereafter, the size, shape, and density of the catalyst particles withinthe catalyst bed 18 are to be essentially uniform and are selected inaccordance with the designed maximum rate of flow of feed streams or amixture 34 of the hydrogen-containing gas 36 and the liquid hydrocarbonstream 38 to prevent ebullation, expansion, or fluidization of thecatalyst bed 18 while the latter progressively moves down through thereactor vessel 10 in layers by plug flow.

A "plug flow" of the catalyst bed 18 is illustrated in FIGS. 4 and 5herein (which are identical to FIGS. 8 and 9 but for reference numeraldescriptors in the fully incorporated copending application Ser. No.08/497,638 filed Jun. 30, 1995) and may be best described as when alowermost volumetric layer A is removed, the next volumetric layer Bflows downwardly to replace the lowermost volumetric layer A and assumesa new position as a lowermost volumetric layer B. The removed lowermostvolumetric layer A is replaced with an upper volumetric layer J. Theprocedure is again repeated (as best shown by the dotted linerepresentations in FIG. 5) by removing the lowermost volumetric layer Band causing the next volumetric layer C to flow downwardly in aplug-like fashion to replace the lowermost volumetric layer B and assumea new position as a lowermost volumetric layer C. The removed lowermostvolumetric layer B is replaced with an upper volumetric layer K. Theprocedure may be continually repeated to define a downwardlyplug-flowing catalyst bed 18 which is moving in direction of arrow W inFIG. 5.

The reactor vessel 10 also contains a generally (grid-like structure)circular plate member 22 (i.e. a distributor tray), that is secured tothe internal generally cylindrical wall 11 such that a plenum (or inlet)chamber 24 is produced between the catalyst bed support means 16 and thegenerally circular plate member 22. A bottom header, generallyillustrated as 40, is defined by the distance between the inner surface13 of the bottom domed closure 12 and the plate member 22. The mixture34 of the hydrogen-containing gas 36 and the liquid hydrocarbon stream38 is supported by the bottom domed closure 12, more specifically by thesurface 13 of the bottom domed closure 12, such as to occupy avolumetric portion in the bottom header 40. The distance between thelevel of the mixture 34 and the plate member 22 defines a static head Swherein a suitable gas head 50 comprises evolved hydrogen-containing gas36A that has originated from the mixture 34 of the hydrogen-containinggas 36 and the liquid hydrocarbon stream 38.

As was previously mentioned and indicated, the term "evolvedhydrogen-containing gas" comprises the hydrogen-containing gas 36 thatis being introduced into the reactor vessel 10 along with the liquidhydrocarbon stream 38, any hydrogen gas that has evolved from the liquidhydrocarbon stream 38 itself, and hydrogen-containing gas 36 thatsolutionized and/or dissolved into and/or with the liquid hydrocarbonstream 38 and which has subsequently evolved from the liquid hydrocarbonstream 38, especially after introduction into the reactor vessel 10.

The plate (grid-like structure) member 22 has a plurality of openings 26that respectively communicate with a plurality of tubes or hollow risers28 that are bound to the plate member 22. Stated alternatively, theplate member 22 includes a plurality or multiplicity of tubes or hollowrisers 28 forming openings 26 through the plate member 22. At least oneof the tubes or hollow risers 28 (preferably all of them) contains atubular bore 29 and at least one aperture or opening 30 and a pair ofopen ends, both generally illustrated as 27.

The length of the tubes or hollow risers 28 may be selected such thatthe suitable gas head 50 is formed underneath the plate member 22and/over the level of the mixture 34 to suppress surges in the feedstream(s) entering the bottom header 40 from the conduit 14. Tubes orhollow risers 28 receive the mixture 34 of hydrogen-containing gas 36and liquid hydrocarbon stream 38 and pass the same through the openings26 to enter the plenum (or inlet) chamber 24.

As the mixture 34 of the hydrogen-containing gas 36 and the liquidhydrocarbon stream 38 flows through the respective hollow risers 28, theevolved hydrogen-containing gas 36A within the static head S (or thesuitable gas head 50) enters or passes through the apertures 30, as bestshown in FIGS. 2 and 3. More specifically and as further best shown inFIGS. 2 and 3, as the mixture 34 flows through conduit 14 and into thebottom header 40, evolved hydrogen-containing gas 36A commences toevolve from the mixture 34 and the suitable gas head 50 begins to form.Continual flow of the mixture 34 into the bottom header 40 fills a lowerportion of each of the hollow risers 28 and a volumetric portion of thebottom header 40 such as to produce the suitable gas head 50, all asbest shown in FIG. 1.

The suitable gas head 50 has a pressure that is greater than thepressure of the mixture 34 such that with continual introduction of themixture 34 into the bottom header 40, the mixture 34 commences to flowup and through each of the hollow risers 28 and out of the openings 26and into the plenum (or inlet) chamber 24. When the suitable gas head 50is formed and/or begins to form, evolved hydrogen-containing gas 36Acommences to flow in direction of the arrows M and through theopening(s) 30 in each of the hollow risers 28; that is, evolvedhydrogen-containing gas 36A commences to flow towards a lower pressurezone.

FIG. 2 illustrates the mixture 34 flowing into each of the hollowriser(s) 28 but not to the point of passing by the opening(s) 30, andevolved hydrogen-containing gas 36A passing in direction of the arrows Mfrom the suitable gas head 50, through opening(s) 30 in each of thehollow risers 28, and into the space in each of the hollow risers 28above the mixture 34 contained therein. Obviously as further shown inFIG. 2, as the mixture 34 commences to flow through the respectivetubular bores 29 and up each of the hollow risers 28, some of thehydrogen-containing gas 36 evolves out of and/or from the mixture 34such as to commingle with and/or admix with the evolvedhydrogen-containing gas 36A entering through opening(s) 30 in the hollowriser(s) 28. FIG. 3 illustrates the mixture 34 flowing in the directionof the arrows P and in a manner of turbulent arrows R and passing eachof the opening(s) 30 in the hollow riser(s) 28 with evolvedhydrogen-containing gas 36A passing and/or flowing in direction ofarrows M from the suitable gas head 50, through opening(s) 30 in each ofthe hollow risers 28, and into the mixture 34 for admixing with thesame.

It has been discovered that by providing each of the hollow risers 28with an aperture 30 wherethrough the evolved hydrogen-containing gas 36Apasses to be admixed with the mixture 34 offers the followingadvantages: (i) provides a good steady and smooth flow ofhydrogen-containing gas 36 and liquid hydrocarbon stream 38 into theplenum (or inlet) chamber 24; (ii) the flow distribution of the mixture34 through the openings 26 of the plate member 22 is insensitive to thelevelness of the circular plate member 22 or to the varying liquid levelin the bottom header 40; (iii) there is intimate remixing ofhydrogen-containing gas 36 (i.e. evolved hydrogen-containing gas 36A andhydrogen-containing gas 36) in each of the hollow risers 28; and (iv)there is a high level of turbulence (see arrows R in FIG. 3) in an upperexit section (i.e. an upper section of each hollow risers 28 contiguousto or at openings 26 of the plate member 22) to promote break-up ofbubbles of hydrogen-containing gas 36 and/or evolved hydrogen-containinggas 36A.

The size of the opening(s) 30 is carefully chosen to control the liquidlevel safely above the bottom of the riser 28 and also safely below theopening(s) 30. If the opening(s) 30 is too large, liquid will cover theopening(s) 30 from a decrease in the size of the gas head 50. If theopening(s) 30 is too small, the liquid level will descend from anincrease in the size of the gas head 50, even to the point where theliquid level will uncover the lower open end 27 of at least one of therisers 28. This uncovered riser would then allow a large burst of gas topass up that riser and disturb the even flow of gas and liquid in theplenum. Those possessing the ordinary skill in the art can readilyadjust the size of the gas head 50, the flow of liquids/gas through theriser(s) 28, and the size of the opening(s) 30 in the riser(s) 28 suchthat the liquid level is maintained between the opening(s) 30 and thelower open end 27 of the riser(s) 28 from the Bernoulli principles foundin any fluid flow or hydraulics engineering book, such as by way ofexample and fully incorporated herein by reference thereto: Momentum,Heat, and Mass Transfer, 2nd Edition by Bennett & Myers c 1962, 1974 byMcGraw-Hill Inc.

Without the opening(s) 30, there would be violent slugging of gas andliquid up the riser(s) 28 at random locations as the rapidly varyingliquid height exposes the bottom open end(s) 27 of different risers 28.This leads to large gas bubbles getting to the bottom of the catalystbed support means 16, rather than the gentle, steady rise of many smallgas bubbles.

Thus, by the practice of the present invention, there is provided adistributor assembly for hydroprocessing a hydrocarbon mixture 34 ofhydrogen-containing gas 36 and liquid hydrocarbon 38 that is flowing(preferably upflowing) through a hydroconversion reaction zonecontaining a bed 18 of catalyst. As previously indicated, the circularplate member 22 has a structure defining at least one opening 26. Atleast one tube member or hollow riser 28 with a tubular bore 29 (seeFIGS. 2 and 3) is bound to the plate member 22 such that the tubularbore 29 communicates with the at least one opening 26. The at least onetube member or hollow riser 28 has at least one tubular aperture oropening 30 in a side thereof. As best shown in FIGS. 2 and 3, opening 30has an axis (not identified) that is normal or perpendicular to an axis(not identified) of the hollow-riser 28.

Thus further by the practice of the present invention, there is providedthe reactor 10 having the internal cylindrical wall 11 and the catalystbed support means 16 secured to the internal wall 11 for supporting thecatalyst bed 18. As previously indicated, the distributor assembly issecured to the internal cylindrical wall 11. More specifically withrespect to the distributor assembly, the plate member 22 is secured tothe cylindrical wall 11 of the reactor 10 and has a structure definingat least one opening 26. More specifically further and as previouslyindicated, the at least one tube member or hollow member 28 of thisinvention, has the tubular bore 29 and is bound to the plate member 22such that the tubular bore 29 communicates with the at least one opening26. Each of the tube members or hollow risers 28 has a tubular opening30 in the side thereof and a pair of open ends.

Thus yet further by the practice of the present invention, there isprovided a method for hydroprocessing a hydrocarbon feed stream that isflowing through a hydrocarbon reaction zone having a bed of catalystcomprising the steps of: (i) forming at least one tubular zone in areactor zone containing a hydrocarbon reaction zone having a bed ofcatalyst; (ii) flowing a mixture of hydrogen-containing gas and liquidhydrocarbon into the reactor zone to produce evolved hydrogen-containinggas; and (iii) flowing the mixture of hydrogen-containing gas and liquidhydrocarbon through the tubular zone while admixing therewith theevolved hydrogen-containing gas.

While the present invention has been described herein with reference toparticular embodiments thereof, a latitude of modification, variouschanges and substitutions are intended in the foregoing disclosure, andit will be appreciated that in some instances some features of theinvention will be employed without a corresponding use of other featureswithout departing from the scope of the invention as set forth.

We claim:
 1. A reactor comprising a vessel with an internal cylindricalwall and having a bottom domed closure; a catalyst bed; a catalyst bedsupport means secured to said internal cylindrical wall of said vesselfor supporting the catalyst bed; a plate member secured to the internalcylindrical wall of the vessel at a position below the catalyst bedsupport means and having a structure defining at least one opening; amixture of a hydrogen-containing gas and a liquid hydrocarbon streamsupported by the bottom domed closure and having a liquid level belowthe plate member; evolved hydrogen-containing gas between the liquidlevel and the plate member; at least one tube member having an openbottom end and a tubular bore and bound to said plate member such thatsaid tubular bore communicates with said at least one opening; and saidat least one tube member including at least one tubular opening in aside thereof, wherein the liquid level is above the bottom end of the atleast one tube member and below the at least one tubular opening in theat least one tube member.
 2. The reactor of claim 1 wherein said tubemember has a tubular axis and said at least one tubular opening has anopening axis that is generally normal to said tubular axis.